Air conditioning apparatus



y 11, 1944. 1.. G. Hueems A 2,353,240

AIR CONDITIONING APPARATUS Filed Aug. 3, 1940 2 Sheets-Sheet l WITNES SES: INVENTOR L2 LEQQY 6. HUGGINS Z? W .FZ'G- 1..

WQM BY 4 ATTORN I July 11, 1944. L, G, HUGGINS 2,353,240

AIR CONDITIONING A PARATUS Filed Aug. 3, 1940 2 Sheets-Sheet 2 1 II I1 is I II WITNESSES: |NVENTQR 7Q fiz@ g%- L2 Laeoy Ci Huasmb ATTORNE Patented July 1 1, 1944 to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application August a, 1940, Serial No. 350,547

11 Claims.

The present invention is an improvement upon the inventionof Charles M. Sanders, Jr., described and claimed in his Patent No. 2,280,425 issued April 21, 1942, and is covered by the broad claims thereof. 7

My invention relates to air conditioning apparatus, more particularly to a refrigerant e aporator for cooling and dehumidifying air and means for controlling the flow of refrigerant in such evaporator.

It is an object of my invention to provide im-' proved apparatus of the character set forth.

Another object is to provide improved means for varying the capacity or cooling effect of the evaporator.

Another object is to provide improved means for reducing the effective portion of the evaporator for partial load operation while at the same time maintaining the effective portion at a sufflciently-low temperature to maintain a desired degree of dehumidification.

A more particular object is to provide improved means for controlling the admission of refrigerant to the evaporator in such manner as to reduce the effective portion of the evaporator, that is, the portion containing liquid refrigerant, in order to provide either reduced capacityfor partial load operation or to provide increased degree of dehumidiflcation.

A preferred embodiment of my invention includes a conventional evaporator of the so-called dry type, including, for example, a plurality of refrigerant passages or coils through which refrigerant flows in parallel and over which the air may flow either in series or in parallel, more commonly in parallel. Liquid refrigerant is distributed to the several coils in any known manner, preferably through orifices or restricted passageways which effect a portion of the expansion or pressure reduction of the refrigerant, and the admission of the refrigerant from a common supply is controlled by a thermostatic expansion valve which includes a temperature-responsive element subjected to the temperature of the vaporized refrigerant discharged from the several coils of the evaporator, the temperature-respo sive element being usually strapped to the suction conduit. Such a valve controls the admission of refrigerant so as to maintain a substantially constant degree of super-heat of such vaporized refrigerant and, accordingly, provides the admission of such quantity of liquid refrigerant as can be fully vaporized in the evaporator. In accordance with the present invention, I provide means for of liquid refrigerant from a portion ofthe refrigerant circuit containing liquid refrigerant at a pressure higher than that existing in the evaporator; for example, between said thermostatic expansion valve and said orifices or restricted passageways. The extracted refrigerant is conveyed to the suction conduit at a point ahead of the temperature-responsive element; so that the latteris thereby subjected to a lower temperature.

in Accordingly, the expansion valve restricts the ad- 15 refrigerant.

These and other objects are effected by myinvention as will be apparent from the following description and claims taken in accordance with the accompanying drawings, formin a part of this application, in which:

Fig. 2 is a detail sectional view showing the refrigerant distributor head from which refrigerant is extracted; and,

Fig. 3- is a diagrammatic view of air conditioningapparatus in which my inventionis employed for the purpose of providing increased degree of dehumidiflcation.

v Figure 1 Referring first to Fig. 1, in which my invenshow an enclosure ll whichds'to be supplied with cooled and dehumidified air. A portion of the air to be conditioned and delivered to the enclosure is withdrawn from the enclosure I0 40 through a nuct ii and another portion is drawn from outdoors through a duct l2. These two portions are mixed and enter an air conditioning chamber ll containing an ..evaporator 14. A

motor-driven fan It draws the air through the chamber I3 and over the evaporator l4 and discharges the same through a duct It to the enclosure II.

The evaporator H is of conventional construction, comprising a plurality of serpentine refrigerant coils II, the coils shown having four tubes.

Liquid refrigerant is supplied under control of an expansion valve I! and is distributed to the inlet ends of the coils by a group of restricted passageways, such. as the distributor tubes IO,

selectively extracting or bleeding a small amount which arealso sometimes referred to as capillary tion is employed for partial load operation, I

adapted to unload the associated cylinders when,

the solenoids are energized. The compressed refrigerant is conveyed through a conduit 25 to a condenser 26, from which the condensed refrigerant is conveyed through a supply conduit 21 to the valve [8.

The valve [8 is of the type commonly known as a thermostatic expansion valve, regulating the admission of liquid refrigerant to the evaporator so as to maintain a predetermined desired degree of superheat of the vaporized refrigerant discharged from the evaporator into the suction conduit 22. It is provided with a thermostatic bulb 28 arranged in contact with the suction conduit 22. The bulb 28 preferably contains fluid similar to that used as refrigerant and provides a pressure varying as a function of the temperature of the vaporized refrigerant. This pressure is communicated to the valve through a tube 29 and is imposed thereon in valve-opening direction. The pressure of the vaporized refrigerant in the conduit 22 is also communicated through a tube 3| and imposed on the valve in valve-closing direction. The resultant of the two pressures is, therefore, a measure of the superheat of the vaporized ,refrigerant,.so that the valve regulates therefrigerant admission so as to maintain said degree of superheat substantiallyconstant. The valve I8 is preferably adjusted for 10 F. superheat.

A by-pass tube or conduit 32 is provided to convey a restricted flow of liquid refrigerant to the suction conduit to be mixed with the vaporized refrigerant leaving the evaporator. The purpose of this is to reduce the temperature imposed on the thermostatic bulb 28, thereby causing the valve l8 to reduce the admission of refrigerant to the evaporator. The inlet end of the tube 32 is connected to a portion of the refrigerant circuit containing liquid. refrigerant at a pressure substantially higher than the refrigerant pressure within the evaporator l4. Preferably, it is connected between the valve l8 and the distributor tubes I9, in which region the pressure is higher than evaporator pressure because of the pressure drop imposed by the distributor tubes I9. In the illustrated embodiment, the tube 32 is connected to the distributor head 20. The outlet end of the tube 32 is connected to the suction conduit 22 at a point in advance of the thermostatic bulb 28. Alternatively, it may be connected to one of the evaporator coils H at a point adjacent the outlet end thereof. A valve 33 is I connected in the tube 32 for controlling the flow therethrou h and is operated by a solenoid 34, the valve being open when the solenoid is energized and closed when the solenoid is deenergized. A throttling valve 30 is also interposed in the tube 32 to vary the flow of refrigerant through the tube. In this embodiment, the valve 30 is manually adjustable. The tube 32 may be of restricted bore to impose restriction on the flow of refrigerant therethrough.

The control for the apparatus includes line conductors L1 and L: which supply electric current, a master or entrance switch 35 and a twostep thermostat T provided with contacts-33 and 31. The thermostat T is arranged to close the contacts 36 as the temperature in the enclosure I exceeds a predetermined value, such as 80 F., and to open the contacts 31 as th temperature exceeds a slightly higher predetermined value, such as 81 F. The contacts 36 control a circuit 38 which controls the motor-compressor unit 23. The solenoids of the unloader mechanisms 24 and the solenoid 34 are connected in parallel, the circuit 39 therefor extending through the contacts 36 and 31 in series. It is to be understood that the illustration of the control is diagrammatic, and that suitable conventional relays andother known expedients and instmmentalities commonly used in the art may readily be applied by,

anyone skilled in the art.

Fig. 1-Operation Consider first that the temperature is above 81, calling for full load operation. This means that the contacts 36 ar closed to efiect operation of the motor-compressor unit. The contacts 31 are open to deenergize the solenoid 34 and close the valve 33 and to deenergize the solenoids of the unloader mechanisms 24, so that all the cylinders of the motor-compressor unit are loaded. The apparatus now operates in a conventional manner. Refrigerant is compressed by the compressor, condensed in the condenser and admitted to the evaporator under the control of the thermostatic expansion valve IB. The refrigerant is distributed to the several coils I1 and evaporated in the coils by the heat extracted from the air flowing over the evaporator. The vaporized refrigerant returns to the motor-compressor unit through the suction conduit 22. Inasmuch as the valve l8 controls the refrigerant in such a manner as to maintain a constant degree of superheat of the discharged refrigerant vapor, preferably about 10 F., it will be apparent that a relatively small and substantially constant portion of each coll adjacent the outlet end will contain refrigerant which has been fully vaporized and is being superheated The remainder of each coll contains liquid refrigerant and is at sufilciently low temperature to cool and dehumidify the air flowing over the evaporator.

The apparatus is designed, by proportloning compressor-capacity to evaporator surface and capacity, so that the air is cooled to a sufficiently low temperature to eifect the desired degree 0! dehumidiflcation of the air.

When the temperature drops to a value between 80 and 81 indicating a reduced cooling demand, partial load operation is provided. At such a temperature, the contacts 31 are closed thereby energizing the several solenoids. The unloader mechanisms 24 unload two of the compressor cylinders, so that the compressor capacity is reduced to one-half. The solenoid 34 opens the valve 33 to by-pass a small portion of the refrigerant flowing through the distributor head 23. The admission of this refrigerant to the suction conduit reduces the temperature of the vaporized refrigerant and of the suction conduit, so that the pressure within the thermostaticbulb 23 is reduced and the expansion valve operates to reduce the admission of liquid refrigerant to the several coils. In the present embodiment, the valve 30 is preferably so adjusted that approxi- "15 mately one-half as much of each coil contains by the evaporator.

aasaaao liquid refrigerant and becomes fully effective as when operating at full load.

In the operation just described, the reduced compressor capacity is balanced by a corresponding reduction in the liquid-containing or fully ef-= fective portion of the evaporator, so that the suction pressure in the evaporator is maintained at a sumciently low value to enable said liquid-containing portion to operate at a sufficiently low temperature to dehumidiiy the air flowing over the evaporator. There is thus provided suitable means for operating at partial load while at the same time maintaining the temperature ofthe effective portion of the evaporator at a sufiiciently low temperature for dehumidification,

Figure 3 In Fig. 3 I Show an air conditioning system incorporating substantially the same means for varying the capacity or liquid containing portion of the evaporator, but in which the same is used to vary the degree of dehumidification effected The parts which are similar to those of Fig. 1 are designated by similar reference numerals, so that it is not necessary to repeat the description thereof. The compressor 23 in this case, is not provided with unloader mechanism but is of constant capacity. It is started and stopped by the thermostat T.

In this embodiment, a regulating valve do is interposed in. the conduit 32 and is operated by a humidostatH, which is responsive to a humidity condition of the air in the enclosure ill, for example, the relative humidity thereof. The humidostat H may, for convenience, be disposed within the return conduit ll, containing air withdrawn from the enclosure.

Fig. '3Opemtimz When the temperature of the air in the enclosure it exceeds a predetermined value, such as 80, the thermostat T closes the contacts Zita and thereby initiates operation of the motor-compressor unit 23. When the temperature of the air in the enclosure It! decreases substantially below the predetermined value, the thermostat T opens the contacts 36-11 to terminate operation of the motor-compressor unit.

During the operation of the motor-compressor unit, the valve ll] regulates the restricted flow of refrigerant through the by-pass tube 32. The humidostat H moves the valve in opening direction to increase the fiow of refrigerant through the tube 32 upon increase in the relative humidity of the air. The increased flow of refrigerant reduces the temperature of the refrigerant in the suction conduit 22 and causes the thermostatic bulb 28 to move the valve 18 in closing direction. The admission of refrigerant to the evaporator is reduced, thereby reducing the portion of the evaporator containing liquid refrigerant. Since the compressor capacity remains constant, this action results in reduced temperature of the refrigerant in'the evaporator. The reduced temperature cools the air to a lower temperature and thereby effects a greater degree of dehumidification thereof,

Upon decrease in humidity of the air, the humidostat H moves the valve 40 in closing direction to decrease the flow of refrigerant through the tube 32. The temperature of the refrigerant flowing through the suction conduit 22 is increased so that the valve |8 increases the flow of refrigerant to the evaporator. Liquid refrigthe evaporator and it operates at higher temperature, effecting a-lesser degree of dehumidification but effecting a greater removal of sensible heat.

The novelty of the present invention resides particularly in connecting the inlet end of the tube 32 to a part of the refrigerant circuit wherein the pressure is substantially greater than the evaporator pressure, in order to obtain effective flow of refrigerant through the tube 32.

While I have shown my invention in. several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

1. In a refrigerating system, the combination of an evaporator, a thermostatic expansion valve operating to regulate the flow of refrigerant to said evaporator in response to the superheat of the vaporized refrigerant leaving the same and including an element responsive to the temperature of said leaving refrigerant, means providing restricted flow of liquid refrigerant from a portion of the refrigerant circuit containing liquid refrigerant at a pressure substantially higher than the refrigerant pressure within the evaporator and utilizing said restricted flow of liquid refrigerant to reduce the temperature to which said element is subjected, whereby said valve restricts the flow of refrigerant to said evaporator and the portion of the evaporator containing liquid refrigerant is reduced, and means for controlling said restricted flow.

2. A refrigerating system as set forth in claim 1 wherein said restricted flow is controlled in response to the wmperature of the air in the enclosure.

3. A refrigerating system as set forth in claim 1 wherein said restricted flow is controlled in response to humidity of air.

4. An air conditioning system as set forth in claim 1 and including means for simultaneously controlling said restricted flow and the capacity of said compressor means in response to the temperature of the air in said enclosure.

5. Air conditioning apparatus as set forth in claim 1 and further including means for controlling said restricted flow in response to the humidity of the air in said enclosure and for controlling said compressor in response to the temperature of the air in said enclosure.

6. In a. refrigerating system, the combination of an evaporator comprising a plurality of re frigerant passages, expansion mechanism including a thermostatic expansion valve common to said passages and a plurality of restricted passageways for distributing refrigerant to the several passages, the parts being connected for flow of erant extends throughout a greater portion of refrigerant through the valve, the restricted passageways and the evaporator in the order stated, said thermostatic expansion valve operating to regulate the flow of refrigerant to the evaporator in response to the superheat of the vaporized refrigerant leaving said evaporator and including an element responsive to the temperature of said leaving refrigerant, means providing a restricted flow of refrigerant from the refrigerant flowing between said valve and said restricted passageways, and utilizing said restricted flow to reduce the temperature to which said element is subjected, whereby said thermostatic expansion valve reduces the flow of refrigerant to the severa] evaporator passages and the portion of each passage containing liquid refrigerant is reduced, and means for controlling said restricted flow.

7. In refrigerating apparatus, the combination of a refrigerating system including an evaporator, expansion mechanism including a thermostatic expansion valve and a restricted passageway, the parts being connected for flow of refrigerant through the valve, the restricted passageway and the evaporator in the order stated, said thermostatic expansion valve operating to regulate the flow of refrigerant to the evaporator in response to the superheat to maintain the same substantially constant and including an element responsive to the temperature of the refrigerant leaving said evaporator, means providing a restricted flow of refrigerant from the refrigerant flowing between said valve and said restricted passageway, to the vaporized refrigerant leaving said evaporator at a point ahead of said temperature-responsive element for reducing the temperature to which said element is subjected, and means responsive to increase and decrease in humidity of air for initiating and terminating said flow,

8. In a refrigerating system, the combination of an evaporator, a valve for controlling flow of liquid refrigerant to the evaporator, means for controlling said valve, said last mentioned means including an element responsive to the temperature of the vaporized refrigerant discharged from said evaporator, means for withdrawing a restricted flow of liquid refrigerant from a portion of the refrigerating system containing liquid refrigerant at a pressure higher than the refrigerant pressure existing in said evaporator and utilizing the same to reduce the temperature to which said temperature-responsive element responds, and means for controlling said restricted flow of liquid refrigerant.

9. In a refrigerating system, the combination of an evaporator having a plurality of conduits each having an inlet and an outlet, a refrigerant distributor connected to the inlet of each conduit, a single expansion valve for controlling flow of liquid refrigerant to the distributor, said single expansion valve including an element responsive to the temperature of the vaporized refrigerant discharged from the evaporator, means for withdrawing a restricted flow of liquid refrigerant from a portion of the refrigerating system containing liquid refrigerant at a pressure intermediate that of the supply and the refrigerant pressure existing in the evaporator, said portion being between said valve and the inlets of said conduits, and supplying said withdrawn refrigerant ata point ahead of said temperature responsive element whereby its temperature is reduced, valve means controlling the flow through said withdrawing means, and means responsive to a condition brought about by evaporation of refrigerant in said evaporator controlling said last mentioned valve means.

10. In a refrigerating system, the combination v of an evaporator, a thermostatic expansion valve operating to regulate the flow of refrigerant to said evaporator in response to the superheat of the vaporized refrigerant leaving the same and including an element responsive to the temperature of said leaving refrigerant, means providing restricted flow of liquid refrigerant from a portion of the refrigerant circuit containing liquid refrigerant at a pressure substantially higher than the refrigerant pressure within the evaporator and utilizing said restricted flow of liquid refrigerant to reduce the temperature to which said element is subjected below the temperature of the vaporized refrigerant leaving the evapo rator, whereby said valve restricts the flow of refrigerant to said evaporator and the portion of the evaporator containing liquid refrigerant is reduced, and means for controlling said restricted flow.

11. In a refrigerating system, the combination of an evaporator, a thermostatic expansion valve operating to regulate the flow of refrigerant to said evaporator in response to the superheat of the vaporized refrigerant leaving the same and including an element responsive to the temperature of said leaving refrigerant, means providing restricted flow of liquid refrigerant from a portion of the refrigerant circuit containing liquid refrigerant at a pressure substantially higher than the refrigerant pressure within the evapo rator and reducing the temperature to which said element is subjected by mixing said restricted flow of liquid refrigerant with the refrigerant that has been fully vaporized in the evaporator, whereby said valve restricts the flow of refrigerant to said, evaporator and the portion of the evaporator containing liquid refrigerant is reduced, and means for controlling said restricted flow.

LEROY GALE HUGGINS. 

